Roller apparatus and recording apparatus

ABSTRACT

A roller apparatus includes: a first roller provided in a curved medium transporting path and driven by a power source; and a second roller driven and rotating with a medium nipped between it and the first roller, wherein the second roller is located on a side in which, when the leading end of the medium enters between the rollers, the leading end of the medium comes into contact with the second roller due to the restoring force of the medium with a curved state as a result of the curved medium transporting path, and has on its outer circumferential surface a guide section for guiding the leading end of the medium between the rollers.

BACKGROUND

1. Technical Field

The present invention relates to a roller apparatus which includes a first roller driven by a power source, and a second roller driven and rotating with a medium nipped between it and the first roller and provided in a curved medium transporting path. Also, the invention relates to a recording apparatus typified by a facsimile, a printer, and the like, including the above-mentioned roller apparatus.

2. Related Art

In a recording apparatus typified by a facsimile, a printer, and the like, a configuration in which a plurality of rollers are provided in a transporting path for transporting papers and especially, in which paper is transported nipped between two rollers provided to face each other is widely used. Further, there are also many cases where the rollers are provided in a curved medium transporting path, and by the combination of a first roller driven by a motor and a second roller disposed facing the first roller, the paper is transported downstream against the transportation load produced by the paper. (For example, refer to JP-A-2007-253467).

The paper with a curved state given in the curved paper transporting path has self-returning behavior, namely, a tendency (a restoring force) to try to return to its original alignment, and therefore when the leading end of the paper enters between the first roller and the second roller, the paper comes into contact with the circumferential surface of any one of the rollers due to the self-returning behavior, and is then conducted between the rollers along the circumferential surface of the roller.

However, if the contact angle becomes larger, the force necessary to make the paper reach between the rollers becomes greater. Therefore, it is necessary that the motor for driving the transporting roller provided upstream is powerful, and accordingly, there is a danger that the paper will collide strongly with the path member constituting the paper transporting path, resulting in deformation or damage of the path member.

SUMMARY

An advantage of some aspects of the invention is that even if the leading end of a piece of paper rushes onto a roller at a large irruption angle due to the restoring force of the paper in a curved paper transporting path, the leading end of the paper is smoothly conducted between the rollers without being strongly pushed from the rear.

According to a first aspect of the invention, there is provided a roller apparatus including: a first roller provided in a curved medium transporting path and driven by a power source; and a second roller driven and rotating with a medium nipped between it and the first roller, wherein the second roller is located on a side in which, when the leading end of the medium enters between the rollers, the leading end of the medium comes into contact with the second roller due to the restoring force of the medium with a curved state as a result of the curved medium transporting path; and having on its outer circumferential surface a guide section for guiding the leading end of the medium between the rollers.

According to this aspect, since the second roller, which is located on a side in which the leading end of the medium comes into contact with the second roller due to the restoring force of the medium, has on its outer circumferential surface a guide section for guiding the leading end of the medium between the rollers (the first roller and the second roller), even if the leading end of the medium comes into contact with the second roller at a large contact angle, the leading end of the medium can be smoothly conducted between the rollers (to a nip point between both rollers) by the guide section. Therefore, the leading end can be smoothly conducted between the rollers without being strongly pushed from the rear.

According to a second aspect of the invention, in addition to the first aspect, the first roller is located on a side in which, when the tail end of the medium has been withdrawn from between the rollers, the tail end of the medium comes into contact with the first roller due to the restoring force of the medium with a curved state as a result of the curved medium transporting path.

According to this aspect, since the first roller driven by a power source is located on a side in which the tail end of the medium comes into contact with the first roller due to the restoring force of the medium, after the tail end of the medium has been withdrawn from between both rollers, the tail end of the medium comes into contact with the first roller, i.e., the roller which does not have a guide section provided on its circumferential surface. Therefore, after the tail end of the medium has been withdrawn from between the rollers, the medium is not strongly pushed downstream by the guide section, whereby loss of transportation accuracy after the withdrawal of the tail end of the medium from between the rollers can be prevented.

According to a third aspect of the invention, in addition to the first or the second aspect, the guide section includes grooves formed at suitable intervals along the outer circumferential direction of the second roller and extending in a lengthwise direction of the roller.

According to this aspect, since the guide section includes grooves formed at suitable intervals along the outer circumferential direction of the second roller and extending in a lengthwise direction of the roller, the leading end of the medium can be reliably conducted between the rollers.

According to a fourth aspect of the invention, in addition to any one of the first to the third aspects, the outer circumference of the second roller includes a first region facing the first roller, and a second region disposed on one side or both sides of the first region and having a larger outer diameter than that of the first region, and the guide section is provided in the second region.

According to this aspect, since the second roller has on its outer circumference the first region facing the first roller, and the second region disposed on one side or both sides of the first region, and the guide section is provided in the second region, the leading end of the medium can be reliably conducted between the rollers without the guide section damaging the surface of the medium.

According to a fifth aspect of the invention, there is provided a recording apparatus including a recording unit for performing recording on a medium, wherein the roller apparatus according to any one of the first to the fourth aspects is provided in a curved transporting path for transporting the medium. According to this aspect, in the recording apparatus, an operation and an effect identical to those of any one of the first to the fourth aspects can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.

FIG. 1 is a side sectional elevation view showing the paper transporting path of an ink jet printer according to the invention.

FIG. 2 is a front view (including a partly enlarged view and a diagram as viewed from the direction of an arrow) of inversion rollers and assistance rollers.

FIG. 3 is a side view of the assistance roller.

FIGS. 4A to 4D are front views of the rollers, showing other embodiments of the assistance roller.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, embodiments of the invention will be described with reference to FIGS. 1 to 3 and 4A to 4D. FIG. 1 is a side sectional elevation view showing the paper transporting path of an ink jet printer (hereinafter referred to as a “printer”) 1 which is an embodiment of a “recording apparatus” according to the invention, FIG. 2 is a front view (including a partly enlarged view and a diagram as viewed from the direction of an arrow) of inversion rollers 50 and assistance rollers 51, FIG. 3 is a side view of the assistance roller 51, and FIGS. 4A to 4D are front views of the rollers, showing other embodiments of the assistance roller. Also, although FIG. 1 depicts almost all the rollers on the same plane in order to show rollers disposed on the paper transporting path of the printer 1, their positions in a depth direction (the direction from the front to the rear of the paper of FIG. 1) cannot be said to necessarily be in agreement. (There is also a case where they are in agreement.)

Hereinafter, referring to FIG. 1, the entire configuration of the printer 1 will be generally described. The printer 1 includes a feeding apparatus 2 provided at the lower portion thereof and has a configuration in which the media to be recorded (recording paper mainly consisting of single sheets: hereinafter referred to as a “paper P”) as an example of a “medium” are fed one by one from the feeding apparatus 2, recorded (ink jet recorded) on at a recording unit 4, and then discharged toward a paper discharging stacker (not shown) provided on the front side of the printer (the right side in FIG. 1).

Further, the printer 1 includes an inversion unit 7 detachably provided at the rear portion thereof. At the inversion unit 7, the paper P is curved and inverted such that the second face opposite to the first face of the paper P on which recording has first been made faces a recording head 42, and as a result, recording can be carried out on both sides of the paper P.

Components on the paper transporting path will be described in more detail below.

The feeding apparatus 2 includes a paper cassette 11, a pick-up roller 16, a guide roller 20, and a separating means 21.

Plural pieces of the paper P can be set in a stacked state in the paper cassette 11 which can be mounted on and separated from the front side of the printer, and are positioned at a feeding position by edge guides (not shown).

The pick-up roller 16 rotationally driven by a motor (not shown) is provided at a rocking member 17 rocking about a pivot shaft 18, and rotates in contact with the uppermost one of the papers P set in the paper cassette 11, thereby sending out the uppermost paper P from the paper cassette 11.

A separating inclined plane 12 is disposed at a position facing the leading ends of the paper P set in the paper cassette 11, and the paper P sent out by the rotation of the pick-up roller 16 advances downstream with its leading end in sliding contact with the separating inclined plane 12, whereby a preliminary separation of the paper from the next paper P is carried out.

The freely rotatable guide roller 20 is provided on the downstream side of the separating inclined plane 12, and the separating means 21 configured to include a separating roller 22 and a driving roller 23 is provided on the downstream side of the guide roller 20. The separating roller 22 has an outer circumferential surface formed of an elastic material and is provided to be able to be in pressure-contact with the driving roller 23, and further provided in a state in which a predetermined rotational resistance is given thereto by a torque limiter mechanism.

Therefore, the next paper P trying to be transported while overlapped is blocked between the separating roller 22 and the driving roller 23, that is, transportation of the overlapping paper is prevented. Further, the driving roller 23 is rotationally driven by the motor (not shown) in a direction to send the paper P downstream.

On the downstream side of the separating means 21, there is provided a first intermediate feed section 25 configured to include a driving roller 26 rotationally driven by the motor (not shown), and an assistance roller 27 driven and rotating with the paper P nipped between it and the driving roller 26, and the paper P is sent out further downstream by the first intermediate feed section 25.

The printer 1 has a curving and inverting path for curving and inverting the paper P sent out from the paper cassette 11 such that its advancing direction becomes the opposite direction, as shown in the drawing, and on the downstream side of the first intermediate feed section 25, there is provided a driven roller 29 for alleviating the paper-through load when the paper P passes through the curving and inverting path (in particular, when the tail end of the paper passes through).

On the downstream side of the driven roller 29, there is provided a second intermediate feed section 31 configured to include a driving roller 32 rotationally driven by the motor (not shown), and an assistance roller 33 driven and rotating with the paper P nipped between it and the driving roller 32, and the paper P is sent out further downstream by the second intermediate feed section 31.

On the downstream side of the second intermediate feed section 31, the recording unit 4 is disposed. The recording unit 4 includes a transporting means 5, the recording head 42, a front paper guide 39, and a discharging means 6. Further, a paper detecting means (not shown) for detecting the passage of the paper P is also provided near to the upstream side of the transporting means 5.

The transporting means 5 is configured to include a transportation driving roller 35 rotationally driven by the motor, and a transportation driven roller 36 pivotally supported by an upper paper guide 37 to be driven and rotated in pressure-contact with the transportation driving roller 35. The paper P which has reached the transporting means 5 is precisely transported downstream by the rotation of the transportation driving roller 35 with the paper nipped between the transportation driving roller 35 and the transportation driven roller 36.

Subsequently, the recording head 42 is provided at the bottom portion of a carriage 40, and the carriage 40 is driven by a driving motor (not shown) to reciprocate in the main scanning direction (the direction from the front to the rear of the paper of FIG. 1) while being guided on a carriage guide shaft 41 extending in the main scanning direction. Also, the carriage 40 is of a so-called off-carriage type on which an ink cartridge is not mounted, and thus configuration is provided in which the ink cartridge (not shown) is provided independently of the carriage 40 and ink is supplied from the ink cartridge to the recording head 42 through an ink supply tube (not shown).

The front paper guide 39 is provided at a position facing the recording head 42, and the distance between the paper P and the recording head 42 is defined by the front paper guide 39. Also, on the downstream side of the front paper guide 39, there is provided the discharging means 6 for discharging the paper P on which recording has been made. The discharging means 6 is configured to include a discharge driving roller 44 rotationally driven by the motor (not shown), and a discharge driven roller 45 driven and rotating in contact with the discharge driving roller 44, and the paper P on which recording has been made by the recording unit 4 is discharged to a stacker (not shown) provided on the front side of the printer, by the discharging means 6.

Subsequently, the inversion unit 7 will be described. The inversion unit 7 includes inversion rollers 50 of a large diameter and assistance rollers 51 and 52 driven and rotating with the paper P nipped between them and the inversion rollers 50. The paper P with recording made on the first face thereof, which comes from the paper cassette 11, is drawn and entered between the inversion roller 50 and the assistance roller 52 with the side, which became the tail end of the paper when recording was carried out on the first face, now becoming the leading end, due to a reverse feed operation of the second intermediate feed section 31, the transporting means 5, and the discharging means 6.

The inversion rollers 50 are rotationally driven by a motor (not shown) in a counter-clockwise direction as viewed in FIG. 1, and the paper drawn and entered between the inversion rollers 50 and the assistance rollers 52 passes between the inversion rollers 50 and the assistance rollers 51 to reach the second intermediate feed section 31 again, and subsequently, recording is carried out in the same manner by the recording unit 4.

The foregoing is a summary of the printer 1. Next, the assistance rollers 51 will be explained in detail with reference to FIGS. 2 and 3. The inversion unit 7 as the “roller apparatus” according to the invention includes the inversion roller 50 as a “first roller”, and the assistance roller 51 as a “second roller”.

In FIG. 2, the inversion roller 50 is configured to include a roller main body 50 a and an elastic member 50 b wound on the outer circumferential portion of the roller main body to form the outer circumferential surface of the inversion roller 50. The roller main body 50 a is formed integrally with a rotating shaft 49 extending in the widthwise direction of the paper, by resin molding, and provided in a plurality (4 pieces in this embodiment) at intervals in an axial direction of the rotating shat 49, as shown in the drawing.

As the elastic member 50 b, a rubber material, for example, EPDM (ethylene-propylene rubber), NBR (nitrile rubber), CR (chloroprene rubber), or the like can be used, otherwise, various thermal plastic elastomers such as styrene series and olefin series, or the like can also be used.

The assistance roller 51 acting to nip the paper P along with the inversion roller 50 is integrally formed as a whole by a injection molding process using a resin material such as POM (polyacetal resin), and therefore its outer circumferential surface which nips the paper P along with the inversion roller 50 is also formed by the molding process. Also, reference numeral 51 a denotes a shaft member which is a member separate from the assistance roller 51 and which passes through the shaft hole of the assistance roller 51, thereby becoming the rotating shaft of the assistance roller 51.

Here, the width WB of the outer circumferential surface of the assistance roller 51 in contact with the paper P is defined to be greater than the width WA of the outer circumferential surface of the inversion roller 50. Also, in a state in which the outer circumferential surfaces of the inversion roller 50 and the assistance roller 51 face each other, parting lines (P•L) formed on the outer circumferential surface of the assistance roller 51 by the molding process of the assistance roller 51 are disposed at places deviated from a region (corresponding to the region of the width WA: hereinafter referred to as a “pressing region”) where the paper P is nipped between both rollers.

Further, all of the opposite end portions of the outer circumferential surface of the assistance roller 51 in contact with the paper P are disposed to deviate from the region facing the outer circumferential surface of the inversion roller 50 (to deviate from the pressing region). Therefore, it is possible to prevent the parting lines (P•L) or the opposite end portions (corner portions) of the outer circumferential surface of the assistance roller from being strongly pressed against the paper P, whereby damage of the recorded surface of the paper P, caused by the parting lines (P•L) or the opposite end portions of the outer circumferential surface of the assistance roller, is prevented.

Further, in a case where the outer circumferential surface of the inversion roller 50 has more elasticity (is softer) than the outer circumferential surface of the assistance roller 51, if the width WB of the assistance roller 51 is smaller than the width WA of the inversion roller 50, a state in which the assistance roller 51 becomes buried in the outer circumferential surface of the inversion roller 50 occurs, and as a result there is a danger that deformation or the like of the paper P will be caused. However, as described above, since the width WB of the assistance roller 51 is greater than the width WA of the inversion roller 50, the occurrence of such a problem can also be prevented.

Next, in the outer circumferential surface of the assistance roller 51, a plurality of grooves 51 b each extending in a lengthwise direction of the assistance roller (an axial direction of the rotating shaft 51 a) are formed at regular intervals along the outer circumferential direction of the assistance roller, thus causing the following operation and effect. Namely, in FIG. 3, the leading end (denoted by the symbol Pa) of the paper entering between the inversion roller 50 and the assistance roller 51 is formed into a curved state by the passage of the paper along the curved transporting path, and accordingly the leading end tries to come into contact with the outer circumferential surface of the assistance roller 51 due to restoring force (self-returning behavior, namely, behavior trying to return to an original flat alignment), as shown by an arrow Fa in FIG. 3. In other words, the assistance roller 51 is located on such a side.

As described above, although the assistance roller 51 is disposed on a side with which the leading end Pa of the paper comes into contact, since the grooves 51 b are formed in the outer circumferential surface of the assistance roller 51, the leading end Pa of the paper is smoothly guided to a nipping point between the inversion roller 50 and the assistance roller 51 by the groove 51 b. Therefore, even if the leading end Pa of the paper comes into contact with the assistance roller 51 at a large contact angle, the leading end Pa of the paper can be reliably conducted between the rollers by a guide section comprised of the grooves 51 b without being strongly pushed from the rear.

Further, after the tail end (denoted by the symbol Pb) of the paper has been withdrawn from between both rollers, due to the curved state of the paper, the tail end Pb of the paper comes into contact with the outer circumferential surface of the inversion roller 50 due to the restoring force of the paper, as shown by an arrow Fb. Since the guide section (grooves 51 b) is not formed in the outer circumferential surface of the inversion roller 50, after the tail end Pb of the paper has been withdrawn from between both rollers, the paper is not strongly pushed downstream, thus preventing loss of transportation accuracy.

Further, the embodiment described above is only an example, it is needless to say that the invention is not limited to this, and the assistance roller 51 can be appropriately changed with regard to its configuration, material, manufacturing method, and the like. For example, assistance rollers 53 to 56 shown in FIGS. 4A to 4D, respectively, are all different embodiments of the assistance roller 51 and, for further example, the grooves acting as the guide section formed in the outer circumferential surface of the assistance roller may also be formed into an inclined groove such as a groove 53 a in FIG. 4A or a V-shaped groove such as a groove 54 a in FIG. 4B.

Further, as the guide section, grooves are not necessarily formed in the outer circumferential surface of the roller, but it is also possible to provide an elastic material 55 a (FIG. 4C) having elasticity to such an extent that the leading end of the paper can break into it, on the outer circumferential surface of the roller, thereby making it serve as the guide section.

Also, as shown in FIG. 4D, the outer circumference of the assistance roller 56 is constituted of a first region 56 a facing the inversion roller 50, and second regions 56 b and 56 b located on both sides of the first region 56 a and larger in outer diameter than the first region 56 a, and the guide section may be provided in the second regions 56 b and 56 b. Further, in the embodiment of FIG. 4D, the guide section is constituted by a groove (a groove formed in a plurality of numbers at suitable intervals along the outer circumferential direction of the roller and extending in a lengthwise direction of the roller) which is identical to the groove 51 b formed in the assistance roller 51.

With the configuration described above, the paper is nipped between the inversion roller 50 having a smooth outer circumferential surface without concavities and convexities, and the first region 56 a similarly having a smooth outer circumferential surface without concavities and convexities, whereby damage of the surface of the paper by the guide section provided in the outer circumferential surface of the roller can be prevented. 

1. A roller apparatus comprising: a first roller provided in a curved medium transporting path and driven by a power source; and a second roller driven and rotating with a medium nipped between it and the first roller, wherein the second roller is located on a side in which, when the leading end of the medium enters between the rollers, the leading end of the medium comes into contact with the second roller due to the restoring force of the medium with a curved state as a result of the curved medium transporting path, and has on its outer circumferential surface a guide section for guiding the leading end of the medium between the rollers.
 2. The roller apparatus according to claim 1, wherein the first roller is located on a side in which, when the tail end of the medium has been withdrawn from between the rollers, the tail end of the medium comes into contact with the first roller due to the restoring force of the medium with a curved state as a result of the curved medium transporting path.
 3. The roller apparatus according to claim 1, wherein the guide section includes grooves formed at suitable intervals along the outer circumferential direction of the second roller and extending in a lengthwise direction of the roller.
 4. The roller apparatus according to claim 1, wherein the outer circumference of the second roller includes a first region facing the first roller, and a second region disposed on one side or both sides of the first region and having a larger outer diameter than the first region, and the guide section is provided in the second region.
 5. A recording apparatus comprising a recording unit for performing recording on a medium, wherein the roller apparatus according to claim 1 is provided in a curved transporting path for transporting the medium. 